Non-evaporation type getter, display unit and production method for them

ABSTRACT

Disclosed are a non-evaporation type getter excellent in gettering effect, capable of maintaining the inside of a gas-tight container in a display apparatus, particularly a flat panel display apparatus or the like, in a high vacuum condition, easy to mount and less liable to contaminate the inside of the gas-tight container, a display apparatus including the getter, and methods of manufacturing the same. The non-evaporation type getter ( 20 ) includes a molded body including at least one element selected from the group consisting of Ti, Zr, Al, V, and Fe as a principal constituent thereof, the molded body formed by powder injection molding. The molded body is composed of a porous body having a porosity of 10 to 30%.

TECHNICAL FIELD

[0001] The present invention relates to a non-evaporation type getter, adisplay apparatus, and methods of manufacturing the same.

BACKGROUND ART

[0002] In recent years, there have been proposed flat panel displayapparatuses in which phosphors are irradiated with electron beamsemitted from electron emission sources such as field emission devices,to cause the phosphors to emit light, thereby forming an image, such asa field emission display (hereinafter abridged to FED).

[0003] In an FED, a substrate provided with electron emission sourcesarranged in a matrix form and a substrate provided with phosphors aredisposed opposite to each other with a minute gap therebetween, theperipheries of the substrates are sealed to form a gas-tight container,the inside of the gas-tight container is maintained in a high vacuum orultrahigh vacuum, and the phosphors are irradiated with electron beamsemitted from electron emission sources, to cause the phosphors to emitlight, thereby displaying an image.

[0004] For an assured operation of the FED, it is necessary to maintainthe inside of the gas-tight container formed between the substrates inan ultrahigh vacuum (a pressure of not higher than about 1×10⁻⁶ Pa).This is because, at a lower degree of vacuum (namely, at a higherpressure), field emission devices used as the electron emission sourcesare contaminated, leading to a trouble regarding the electron emissioncharacteristics (emission characteristics), and to shorten the life ofthe FED.

[0005] Thus, in a flat panel display apparatus including therein agas-tight container with a high degree of vacuum, such as the FED, avapor deposition type getter is disposed inside a getter chamberdisposed at an end portion of the gas-tight container, in order toenhance the degree of vacuum inside the gas-tight container by thegettering effect. In addition, provision of a non-evaporation typegetter inside the gas-tight container has also been proposed.

[0006] In the flat panel display apparatus such as the FED, the gapbetween a front substrate and a back substrate is as minute as about 1.5mm or less, and it is difficult to bring the inside space to anultrahigh vacuum, but it is important to maintain all locations in theinside space at a uniform degree of vacuum. Besides, in an operation ofthe FED, the irradiation of a phosphor surface with electrons dischargedfrom the field emission devices causes liberation of a gas or gases.When a gradient of the degree of vacuum is generated as a result of theliberation of a gas or gases, in the region where the field emissiondevices are formed on the back substrate the field emission devices maybe contaminated depending on the location, and the emissioncharacteristics at the contaminated portions are degraded, resulting ina shortening of the life of the FED. Therefore, with only the vapordeposition type getter disposed only at an end portion of the gas-tightcontainer, generation of a gradient of the degree of vacuum cannot beobviated. In view of this, in the flat panel display apparatuses such asthe FED, the need to dispose non-evaporation type getters in a dispersedmanner has been increasing, in order to maintain the inside of thegas-tight container at a uniform ultrahigh vacuum.

[0007] Conventionally, the non-evaporation type getters have been formedby vapor deposition or sputtering. In the formation of thenon-evaporation type getters, it is necessary to form thenon-evaporation type getters at positions for avoiding the fieldemission device pattern and the phosphor pattern, resulting in adifficulty on a manufacturing process basis that an accurate maskingtreatment is needed. If the masking is unsatisfactory and the fieldemission devices are contaminated due to vapor deposition or the like, atrouble as to emission characteristics is generated, and the life of theflat panel display apparatus such as the FED is shortened.

[0008] Incidentally, there have also been proposed some methods offorming non-evaporation type getters by a film forming process otherthan vapor deposition and sputtering. For example, Japanese PatentLaid-open No. Hei 5-159697 proposes a method of producing anon-evaporation type getter by a powder processing molding or powderpress molding sintering technique.

[0009] According to the method disclosed in the publication, however,cracking or deformation is liable to occur at the time of sintering dueto such causes as a distribution of shrinkage factor, so that there isthe limitation that it is impossible to form a non-evaporation typegetter having a complicated shape. Besides, the powder molding leads tothe problem of dusting.

[0010] As a method of disposing and fixing a non-evaporation type getterformed by the powder press molding sintering technique or the like inthe inside of a flat panel display apparatus, there has been proposed amethod of fixing the non-evaporation type getter by use of an adhesive,as disclosed, for example, in Japanese Patent Laid-open No. 2000-311638.In the method, however, it is difficult to achieve masking at the timeof applying the adhesive. Besides, depending on the kind of theadhesive, a gas may be liberated from the adhesive during or after athermal activating treatment of the getter, leading to a lowering of thegas absorbing capability of the getter or to contamination of the fieldemission devices, with the result of degradation of the emissioncharacteristics. In addition, to obviate such an inconvenience, it isnecessary to devise a measure for preventing the liberation of gas fromthe adhesive.

[0011] Thus, particularly in a flat panel display apparatus, it has beenvery difficult to dispose the non-evaporation type getter.

[0012] The present invention has been made in consideration of theabove-mentioned circumstances. Accordingly, it is a first object of thepresent invention to provide a non-evaporation type getter which isexcellent in gettering effect, capable of maintaining the inside of agas-tight container in a display apparatus, particularly in a flat paneldisplay apparatus or the like, in a high vacuum condition, easy to mountand less liable to contaminate the inside of the gas-tight container, adisplay apparatus including the getter, and methods of manufacturing thesame.

[0013] It is a second object of the present invention to provide a flatdisplay apparatus capable of enhancing the reliability characteristic ofemission of electron beams from electron emission sources such as fieldemission devices and contriving a longer life, and a method ofmanufacturing the same.

DISCLOSURE OF INVENTION

[0014] In order to attain the first object, according to the presentinvention, there is provided a non-evaporation type getter whichincludes a molded body including at least one element selected from thegroup consisting of Ti, Zr, Al, V, and Fe as a principal constituent,the molded body formed by powder injection molding.

[0015] The non-evaporation type getter according to the presentinvention is comprised of the molded body formed by powder injectionmolding, and, therefore, can have a very complicated shape, as comparedwith non-evaporation type getters produced by a conventional powdersintering technique (for example, the powder press sintering techniquedisclosed in Japanese Patent Laid-open Nos. Hei 8-225806 and Hei5-159697). This is due to the fact that, in the powder injectionmolding, a kneaded mixture containing a metallic powder as a principalconstituent can be injected into a mold having a complicated shape. Inaddition, even a molded body having a complicated shape has a shrinkagefactor upon sintering which is comparatively stable at all portions, hasa sufficient mechanical strength as a structure body to be mounted in agas-tight container of a display apparatus such as a flat panel displayapparatus, and is free of such problems as dusting.

[0016] Besides, since the non-evaporation type getter according to thepresent invention is comprised of the molded body formed by powderinjection molding, it can be produced as a small non-evaporation typegetter having a complicated shape. As a result, a multiplicity of thenon-evaporation type getters according to the present invention can bedispersedly disposed in a minute gap region between substrates in a flatpanel display apparatus such as an FED, without degrading the voltageresistance characteristic between the substrates and without overlappingwith the patterns of field emission devices and phosphors.

[0017] Preferably, the molded body is comprised of a porous body havinga porosity of 10 to 30%. The porosity of the porous body is morepreferably around 25%.

[0018] When the porosity is too low, the gettering characteristic tendsto be lowered; on the other hand, when the porosity is too high, thestrength of the molded body tends to be lowered.

[0019] The setting the porosity of the molded body within theabove-mentioned range ensures that after the molded body is subjected toa predetermined activating treatment, gas is wastelessly absorbed intothe inside of the molded body through pores.

[0020] Preferably, a coating layer is provided at least on a portion ofthe molded body. The thickness of the coating layer is not particularlylimited, but preferably is about 0.05 to 3 μm.

[0021] Preferably, the coating layer includes at least one elementselected from the group consisting of Ti, Zr, Al, V, and Fe, and isformed on the surface of the molded body by a thin film forming means.The material constituting the coating layer and the materialconstituting the molded body may be same with each other or differentfrom each other. The coating layer may be formed on the entire surfaceof the molded body, on a predetermined one surface of the molded body,or only on a predetermined portion of the molded body. The thin filmforming means for forming the coating layer is not particularly limited,and examples of the method include a vapor deposition method such as anelectron beam vapor deposition method, and a sputtering method.

[0022] The purpose of providing the coating layer is to enlarge theeffective surface area for functioning as the getter, thereby enhancingthe gas absorbing capability, or to form a getter coating layer of amaterial different from the getter material of the molded body itself,thereby controlling the gas absorbing capability on the basis of eachkind of gas. From this point of view, the coating layer is a getterlayer.

[0023] Preferably, the molded body includes Ti as a principalconstituent, and the coating layer includes Zr as a principalconstituent.

[0024] As for the gas absorbing capability of the non-evaporation typegetter produced by use of the electron beam vapor deposition method, Zrused singly can provide a higher capability than does Ti used singly. Inthe case of Ti used singly, it is easier to obtain a vapor-depositedfilm with a multi-columnar structure having a larger gas-absorbing area,as compared with the case of Zr used singly. However, in the case of Zrvapor-deposited singly, the gas absorbing capability per unit area isgreater, as compared with the case of Ti vapor-deposited singly.

[0025] In the present invention, by composing the molded bodyprincipally of Ti and composing the coating layer principally of Zr, itcan be expected to obtain a non-evaporation type getter having theadvantages of both Ti and Zr.

[0026] The non-evaporation type getter according to the presentinvention is mounted in a gas-tight container of a display apparatus,for example. Alternatively, the non-evaporation type getter is mountedto a portion of a cathode structure in a cathode-ray tube. Or, thenon-evaporation type getter is mounted in a gas-tight container formedbetween a front substrate and a back substrate constituting a flat paneldisplay apparatus.

[0027] In order to attain the first object, according to the presentinvention, there is provided a method of manufacturing a non-evaporationtype getter, including the step of performing powder injection moldingwhile using a metallic powder (inclusive of alloy powder) containing atleast one element selected from the group consisting of Ti, Zr, Al, V,and Fe as a principal constituent raw material to thereby obtain amolded body having a predetermined shape.

[0028] According to the method of manufacturing a non-evaporation typegetter of the present invention, it is possible to obtain a morecomplicated and smaller non-evaporation type getter, as compared to thecase of a method of manufacturing a non-evaporation type getter by apowder molding sintering process according to the related art. As aresult, a multiplicity of the non-evaporation type getters according tothe present invention can be dispersedly disposed in a minute gap regionbetween substrates in a flat panel display apparatus such as an FED,without degrading the voltage resistance characteristic between thesubstrates and without overlapping with the patterns of field emissiondevices and phosphors.

[0029] Preferably, the molded body is sintered at a temperature of 60 to90% (preferably, 70 to 80%) based on the sintering temperature at whichthe molded body upon sintering will have a true density of not less than95%.

[0030] In the ordinary powder injection molding, the sinteringtemperature is so selected that the molded body upon sintering will havea true density of not less than 95%. Conventionally, for example in thecase of manufacturing a powder injection molded body including titaniumas a principal constituent, the sintering temperature of the molded bodyhas been 1100 to 1300%.

[0031] In the present invention, the true density of the molded bodyafter sintering is preferably in the range of 70 to 90%. Namely, theporosity of the molded body after sintering is preferably 10 to 30%. Inorder to obtain a molded body with such a porosity, in the manufacturingmethod according to the present invention, the molded body is sinteredat a temperature of 60 to 90% (preferably, 70 to 80%) based on thetemperature at which the true density of the molded body after sinteringbecomes not less than 95%. Therefore, in the present invention, in thecase of manufacturing a powder injection molded body including, forexample, titanium as a principal constituent, the sintering temperatureof the molded body is preferably 850 to 950%.

[0032] In the non-evaporation type getter, for absorbing more gas (thegas is chemically and physically adsorbed onto the getter), it isnecessary to enlarge the effective surface area of the getter. For thisreason, the molded body constituting the getter preferably hasappropriate pores so that the gas penetrates and is absorbed throughoutthe inside of the molded body.

[0033] The means for controlling the porosity of the molded body is notparticularly limited, however, examples of the means include means ofincreasing the amount of a binder added to the raw material for powderinjection molding, and means of reducing the sintering temperature andtime.

[0034] Preferably, the average grain diameter of the metallic powder is10 to 20 μm.

[0035] The grain diameter of the metallic powder, which is related withthe porosity of the powder injection molded body after sintering, ispreferably as small as possible, in order to enhance the gas absorbingcapability (gettering characteristic).

[0036] Preferably, the sintering upon the powder injection molding iscarried out in vacuum. The degree of vacuum is not particularly limited,and is in the range of 1×10⁻³ Pa to 1 Pa, for example. With thesintering carried out in such a vacuum, the effect of degassing from themolded body is promoted, and the oxygen concentration in the molded bodyafter sintering can be suppressed, for example, to about 1 wt % or less.It should be noted, however, that an activating treatment of the moldedbody by heating in vacuum is needed for putting the molded body intoactual operation as a getter, and, therefore, it is unnecessary torigorously control the oxygen concentration in the molded body aftersintering.

[0037] Preferably, a coating layer is formed on at least a part of thesurface of the molded body after sintering, by a thin film formingprocess.

[0038] In order to attain the second object, according to the presentinvention, there is provided a flat panel display apparatus including:

[0039] a back substrate including electron emission sources;

[0040] a front substrate which is so disposed as to define a gas-tightcontainer space between itself and the back substrate, and includesphosphors for emitting light by being irradiated with electron beamsemitted from the electron emission sources; and

[0041] a plurality of non-evaporation type getters which are dispersedlydisposed in the gas-tight container space and each of which includes amolded body including at least one element selected from the groupconsisting of Ti, Zr, Al, V, and Fe as a principal constituent thereof,the molded body formed by powder injection molding.

[0042] In the flat panel display apparatus according to the presentinvention, the non-evaporation type getters according to the presentinvention are dispersedly arranged, so that a gradient or a nonuniformdistribution of the degree of vacuum is suppressed, even in a long-timeoperation of the flat panel display apparatus. Therefore, it is possibleto enhance electron emission characteristic of the flat panel displayapparatus and to contrive a longer life of the display apparatus. Inaddition, when it is enabled to maintain the inside of the gas-tightcontainer in an ultrahigh vacuum by use of only the non-evaporation typegetters disposed in the inside of the gas-tight container, it ispossible to eliminate the need for the getter chamber and the vapordeposition type getter which have been provided in the conventional flatpanel display apparatus.

[0043] Preferably, a spacer or spacers for holding the minute gapbetween the front substrate and the back substrate are provided in theinside of the gas-tight container space.

[0044] The method of mounting the non-evaporation type getters is notparticularly limited, and the non-evaporation type getters arepreferably fixed by fitting into portions of the spacer or spacers.

[0045] Alternatively, a structure may be adopted in which a spacer orspacers for holding the minute gap between the front substrate and theback substrate are provided in the inside of the gas-tight containerspace, and the non-evaporation type getters function also as at least apart of the spacer or spacers.

[0046] Preferably, the non-evaporation type getters are disposed at suchpositions as not to hinder the emission of electron beams from theelectron emission sources toward the phosphors and not to be connecteddirectly to the front substrate or the back substrate.

[0047] Adoption of a floating structure in which the non-evaporationtype getters are not connected directly to the back substrate providedwith the electron emission sources or the front substrate having thephosphors ensures that the voltage resistance characteristic between thesubstrates is not deteriorated. Incidentally, in a flat panel displayapparatus such as an FED, a high voltage of about 5 kV, for example, isimpressed between the substrates.

[0048] In order to attain the second object, according to the presentinvention, there is provided a method of manufacturing a flat paneldisplay apparatus according to the present invention, including thesteps of:

[0049] performing powder injection molding by use of a metallic powdercontaining at least one element selected from the group consisting ofTi, Zr, Al, V, and Fe as a principal constituent raw material to obtainnon-evaporation type getters having a predetermined shape,

[0050] preparing a back substrate including electron emission sources,

[0051] preparing a front substrate including phosphors for emittinglight by being irradiated with electron beams emitted from the electronemission sources,

[0052] preparing a spacer for determining the spacing between the backsubstrate and the front substrate,

[0053] press fitting the non-evaporation type getters into the spacer,and

[0054] joining the back substrate and the front substrate to each other,with the spacer therebetween into which the non-evaporation type gettershave been press fitted, so as to form a gas-tight container spacebetween the substrates.

[0055] In the method of manufacturing a flat panel display apparatusaccording to the present invention, the non-evaporation type getters arefixed by press fitting, whereby emission of gas from an adhesive isobviated. Particularly, the conventional manufacturing method has theproblem of emission of gas from an adhesive in the case where amultiplicity of non-evaporation type getters are dispersedly disposed inthe inside of the gas-tight container of the flat panel displayapparatus; on the other hand, the manufacturing method according to thepresent invention is free of the bad effect of increasing the emissionof gas. Besides, in the manufacturing method according to the presentinvention, the need for masking for vapor deposition on the substrate isabsent, and bad influences of the masking are absent, as contrasted tothe manufacturing method in which the non-evaporation type getters areformed in a predetermined pattern by a vapor deposition process.

BRIEF DESCRIPTION OF DRAWINGS

[0056]FIG. 1 is a general sectional view of a flat panel displayapparatus according to one embodiment of the present invention.

[0057]FIG. 2 is a perspective view showing the relationship between aspacer and a non-evaporation type getter shown in FIG. 1.

[0058]FIG. 3A is an enlarged conceptual diagram of an essential part ofthe non-evaporation type getter according to one embodiment of thepresent invention, and FIG. 3B is an enlarged conceptual diagram of anon-evaporation type getter according to another embodiment of thepresent invention.

[0059]FIGS. 4A to 4D are perspective views illustrating the shapes ofnon-evaporation type getters according to other embodiments of thepresent invention.

[0060]FIG. 5A is a graph showing the gas absorbing capability of thenon-evaporation type getter according to one embodiment of the presentinvention and the gas absorbing capability of a conventionalnon-evaporation type getter, and FIG. 5B is a graph showing the gasabsorbing capability of a non-evaporation type getter according toanother embodiment of the present invention.

[0061]FIGS. 6A to 6C are electron microphotographs of thenon-evaporation type getters according to embodiments of the presentinvention.

[0062]FIG. 7 is an SEM photograph of a non-evaporation type getteraccording to another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0063] Now, the present invention will be described below, based on theembodiments shown in the drawings.

[0064]FIG. 1 is a general sectional view of a flat panel displayapparatus according to one embodiment of the present invention; FIG. 2is a perspective view showing the relationship between a spacer and anon-evaporation type getter shown in FIG. 1; FIG. 3A is an enlargedconceptual diagram of an essential part of the non-evaporation typegetter according to one embodiment of the present invention, and FIG. 3Bis an enlarged conceptual diagram of a non-evaporation type getteraccording to another embodiment of the present invention; FIGS. 4A to 4Dare perspective views illustrating the shapes of non-evaporation typegetters according to other embodiments of the present invention; FIG. 5Ais a graph showing the gas absorbing capability of the non-evaporationtype getter according to one embodiment of the present invention and thegas absorbing capability of a conventional non-evaporation type getter,and FIG. 5B is a graph showing the gas absorbing capability of anon-evaporation type getter according to another embodiment of thepresent invention; FIGS. 6A to 6C are electron microphotographs of thenon-evaporation type getters according to embodiments of the presentinvention; and FIG. 7 is an SEM photograph of a non-evaporation typegetter according to another embodiment of the present invention.

[0065] As shown in FIG. 1, the flat panel display apparatus 2 accordingto one embodiment of the present invention is the so-called FED, whichincludes a front substrate 4, and a back substrate 6 disposed oppositeto the front substrate 4, with a predetermined gap spacing Dtherebetween. The predetermined gap spacing D is, for example, about 1.5mm or less.

[0066] On the inside surface of the back substrate 6, an electronemission source layer 12 is formed in which field emission devices areprovided in a predetermined matrix pattern. On the inside surface of thefront substrate 4, phosphors 14 for emitting light by being irradiatedwith electron beams emitted from the field emission devices in theelectron emission source layer 12 are provided in a predeterminedpattern. Incidentally, while only three phosphors 14 are shown in FIG.1, in practice a multiplicity of phosphors 14 are provided in apredetermined pattern on the inside surface of the front substrate 4,according to the number of pixels.

[0067] A sealing material 8 is provided at the peripheral portionbetween the front substrate 4 and the back substrate 6 so as to form aflat gas-tight container 5 between the substrates 4 and 6. The sealingmaterial 8 is composed of, for example, frit glass, and is formed byapplying frit glass to the peripheral portion between the substrates 4and 6 and heat-sealing the substrates.

[0068] In addition, spacers 10 are disposed at a predetermined gapspacing in the inside of the gas-tight container 5 between thesubstrates 4 and 6 in order to maintain the predetermined gap spacing D.The spacers 10 are composed of a material being electrically insulatingor having a high resistance, and are disposed in the inside of thegas-tight container 5 in such a pattern as not to overlap, in plan view,with the pattern of the phosphors 14 and the pattern of the fieldemission devices in the electron emission source layer 12.

[0069] A getter chamber 30 is connected to the outside surface of aperipheral end portion of the back substrate 6, and the gas-tightcontainer 5 is communicated with the inside of the getter chamber 30through an evacuation hole 31 formed in the peripheral end portion ofthe back substrate 6. In addition, a tip pipe 34 is connected to thelower end of the getter chamber 30. The inside of the gas-tightcontainer 5 is evacuated through the tip pipe 34 by an evacuation deviceor the like, and thereafter the tip pipe 34 is sealed off, whereby theinside of the gas-tight container 5 is hermetically sealed, and theinside is maintained in a vacuum condition. Incidentally, a ring-shapedvapor deposition type getter 32 is disposed in the getter chamber 30.The vapor deposition type getter 32 includes, for example, Ba or thelike as a principal constituent thereof.

[0070] In this embodiment, a plurality of non-evaporation type getters20 are dispersedly disposed in the inside of the gas-tight container 5in such a pattern as not to overlap, in plan view, with the pattern ofthe phosphors 14 and the pattern of the field emission devices in theelectron emission source layer 12. In order to fix the mounting positionof each of the non-evaporation type getters 20, in this embodiment, asshown in FIG. 2, at least some spacers 10 of the plurality of spacers 10disposed in the inside of the gas-tight container 5 are each providedwith fitting holes 11 in a roughly central portion thereof in the heightdirection thereof (in the direction of the predetermined gap spacing D)at a predetermined interval along the longitudinal direction thereof.The fitting holes 11 may be through-holes piercing through the thickness(from the face side to the back side) of the spacer 10, or may bebottomed holes.

[0071] As shown in FIG. 2, the non-evaporation type getter 20 includes agetter main plate 22, and getter sub-plates 24 extending, substantiallyin parallel to each other at a predetermined interval, from the surfaceof the getter main plate 22 in a direction substantially orthogonal tothe surface. The getter main plate 22 and the getter sub-plates 24 havea width Dl smaller than the predetermined gap spacing D. The getter mainbody 22 is provided on its back surface with press-fitting projections26 at the same interval as that of the fitting holes 11 formed in thespacer 10. The press-fitting projections 26 are press fitted into thecorresponding fitting holes 11, whereby the non-evaporation type getter20 can be positionedly fixed to the wall surface of the spacer 10.

[0072] The thicknesses of the getter main plate 22 and the gettersub-plates 24, the lengths of them, the number of the getter sub-plates24 arranged for each getter main plate 22, and the interval ofarrangement are so designed as to avoid the pattern of the phosphors 14and the like.

[0073] The getter main plate 22, the getter sub-plates 24 and the pressfitting projections 26 constituting the non-evaporation type getter 20are integrally molded by powder injection molding which will bedescribed below.

[0074] In the powder injection molding, first, a metallic powder(inclusive of alloy powder) including at least one element selected fromthe group consisting of Ti, Zr, Al, V, and Fe as a principal constituentthereof and a binder are kneaded, to prepare an injection moldingmaterial. The average grain diameter of the metallic powder is notparticularly limited, and is, for example, 10 to 20 am. In addition, thebinder is not particularly limited, and is, for example, aparaffin-propylene based binder.

[0075] Next, the powder injection molding material is injected into theinside of a mold having a cavity in the shape of the non-evaporationtype getter 20 shown in FIG. 2, to obtain a pre-molded body. Then, thebinder contained in the pre-molded body is removed. The process up tothis stage is conducted under substantially the same conditions as thosein the ordinary powder injection molding. It should be noted, however,that the content of the binder may be increased to be greater than thatin the ordinary powder injection molding, in order to raise the porosityof the molded body after sintering.

[0076] Next, in this embodiment, the pre-molded body is sintered, toobtain a molded body composed of a sintered body. The sinteringtemperature is preferably a temperature of 60 to 90% (preferably, 70 to80%) based on a sintering temperature at which the true density of themolded body after sintering becomes not less than 95%.

[0077] In the ordinary powder injection molding, the sinteringtemperature is so selected that the true density of the molded bodyafter sintering will be not less than 95%. Conventionally, in the caseof manufacturing a powder injection molded body including, for example,titanium as a principal constituent thereof, the sintering temperaturefor the molded body has been 1100 to 1300° C.

[0078] In this embodiment, the true density of the molded body aftersintering is preferably in the range of 70 to 90%. Namely, the porosityof the molded body after sintering is preferably 10 to 30%, particularlyaround 25%. In order to obtain a molded body with such a porosity, inthe manufacturing method according to this embodiment, the sintering iscarried out at a temperature of 60 to 90% (preferably, 70 to 80%) basedon the sintering temperature at which the true density of the moldedbody after sintering will be not less than 95%. In this embodiment,therefore, in the case of manufacturing a powder injection molded bodyincluding, for example, titanium as a principal constituent thereof, thesintering temperature for the molded body is preferably 850 to 950° C.

[0079] In the non-evaporation type getter, it is necessary to enlargethe effective surface area, in order to absorb more gas (the gas ischemically and physically adsorbed on the getter). For this reason, themolded body constituting the getter preferably has appropriate pores sothat gas penetrates and is absorbed throughout the inside of the moldedbody.

[0080] In addition, the sintering is preferably carried out in vacuum.The degree of vacuum is not particularly limited, and is, for example,1×10⁻³ Pa to 1 Pa. With the sintering in such a vacuum, the effect ofdegassing from the molded body is promoted, and the oxygen concentrationin the molded body after sintering can be suppressed, for example, toabout 1 wt % or less. It should be noted, however, that since anactivating treatment by heating in vacuum is needed for putting themolded body into practical operation as the getter, it is not necessaryto rigorously control the oxygen concentration in the molded body aftersintering.

[0081] Incidentally, the temperature and time of the activatingtreatment are not particularly limited; for example, the temperature isabout 300 to 500° C., and the time is for example 1 to 5 hr.

[0082] The microstructure of the non-evaporation type getter 20 composedof the powder injection molded body obtained as described above is asshown in FIG. 3A, in which predetermined pores 23 are formed betweengrains of the sintered body 21. Incidentally, as shown in FIG. 3B, anon-evaporation type getter coating layer 25 consisting singly of Zr maybe formed on the surface of the sintered body 21 constituting thenon-evaporation type getter 20 by an electron beam vapor depositionprocess, for example. The film thickness of the coating layer 25 is notparticularly limited, and is preferably about 0.05 to 3 μm, morepreferably about 0.1 to 2 μm.

[0083] In the next place, a method of manufacturing the flat paneldisplay apparatus 2 shown in FIG. 1 will be described.

[0084] The phosphors 14 are applied to the inside surface of the frontsubstrate composed of a transparent glass or the like, by a slurryprocess, a printing process, an electrodeposition process or the likeprocess. In addition, an electron emission source layer 12 in whichfield emission devices are arranged in a predetermined matrix pattern isformed on the inside surface of the back substrate 6 composed of atransparent glass, an opaque glass or the like. The pattern of the fieldemission devices in the electron emission source layer 12 corresponds tothe pattern of the phosphors 14.

[0085] Next, the front substrate 4 and the back substrate 6 are adheredto each other, with a plurality of spacers 10 therebetween, so thattheir inside surfaces are opposed to each other at a predetermined gapspacing D. At least some of the plurality of spacers 10 each have theabove-described non-evaporation type getter 20 fixed thereto by pressfitting, and the plurality of the non-evaporation type getters 20 aredisposed in a uniformly dispersed state along the substrate surfaces.Then, a flat gas-tight container 5 is formed between the substrates 4and 6, by frit sealing with a sealing material 8. Thereafter, anevacuation device is connected to a tip pipe 34, the inside of thegas-tight container 5 is evacuated, and after the inside of thegas-tight container 5 has reached a target degree of vacuum, the tippipe 34 is sealed off, to obtain the flat panel display apparatuscomposed of an FED. Incidentally, during the evacuation of the inside ofthe gas-tight container 5, both the substrates 4 and 6 may be heated forpromoting the evacuation, or a heating treatment for activating thenon-evaporation type getters 20 may be conducted. Besides, in order toput the gettering effect of a vapor deposition type getter 32 intopractice, the getter 32 may be heated to flash by externalhigh-frequency heating.

[0086] In the flat panel display apparatus 2 including the gas-tightcontainer 5 in which an ultrahigh vacuum is obtained in the this manner,an operation as the FED can be performed.

[0087] The non-evaporation type getter 20 according to this embodimentis composed of the molded body formed by powder injection molding, and,therefore, can have a complicated shape as shown in FIG. 2, as comparedwith a non-evaporation type getter produced by a conventional powdersintering process (for example, the powder press sintering processdisclosed in Japanese Patent Laid-open Nos. Hei 8-225806 and Hei5-159697). This is because, in the powder injection molding, a kneadedmixture including a metallic powder as a principal component thereof canbe injected into a mold having a complicated shape. In addition, evenwhere the molded body has a complicated shape, the molded body has asufficient mechanical strength for use as a structure body to be mountedin the gas-tight container 5 of the flat panel display apparatus 2, andis free of such problems as dusting.

[0088] Besides, since the non-evaporation type getters 20 are eachcomposed of the molded body formed by powder injection molding, amultiplicity of the non-evaporation type getters 20 can be dispersedlyarranged in the minute gap region between the substrates 4 and 6 in theflat panel display apparatus 2, without deteriorating the voltageresistance characteristic between the substrates 4 and 6 and withoutoverlapping with the patterns of the field emission devices and thephosphors 14.

[0089] In addition, in this embodiment, the porosity of thenon-evaporation type getters 20 is set within the predetermined range,whereby it is ensured that gases penetrate and are absorbed wastelesslyinto the inside of the sintered body 21 through the pores 23 shown inFIG. 3A or 3B.

[0090] Besides, with the coating layer 25 formed as shown in FIG. 3B, itis possible to enlarge the effective surface area for functioning as thegetter, thereby enhancing the gas absorbing capability, or to form agetter coating layer 25 of a material different from the getter materialof the molded body itself, thereby controlling the gas absorbingcapability on the basis of the kind of the gas.

[0091] As for the gas absorbing capability of the non-evaporation typegetter produced by use of an electron beam vapor deposition process, Zrused singly can have a higher capability than that of Ti used singly.The use of Ti alone has the merit that it is easier to obtain a vapordeposited film with a multi-columnar structure having a larger gasabsorbing area, as compared to the use of Zr alone. On the other hand,however, the vapor deposition of Zr alone leads to a higher gasabsorbing capability per unit area, as compared with the vapordeposition of Ti alone.

[0092] In the embodiment shown in FIG. 3B, with the sintered body 21including Ti as a principal constituent thereof and with the coatinglayer 25 including Zr as a principal constituent thereof, it can beexpected to obtain a non-evaporation type getter 20 having the merits ofboth Ti and Zr.

[0093] In addition, in the flat panel display apparatus 2 shown in FIG.1, the non-evaporation type getters 20 are disposed in a dispersedstate, so that a gradient or nonuniform distribution of the degree ofvacuum can be suppressed, even in a long-time operation of the flatpanel display apparatus. Besides, when it is possible to maintain theinside of the gas-tight container 5 in an ultrahigh vacuum by use ofonly the non-evaporation type getters 20 arranged inside the gas-tightcontainer 5, it is possible to eliminate the need for the getter chamber30 and the vapor deposition type getter 32 provided in the flat paneldisplay apparatus 2.

[0094] Besides, in this embodiment, the non-evaporation type getters 20are arranged at such positions as not to hinder the emission of electronbeams from the electron emission source layer 12 toward the phosphors 14and not to be connected directly to the front substrate 4 and the backsubstrate 6. The adoption of such a floating structure in which thenon-evaporation type getters are not in direct contact with the backsubstrate provided with the electron emission sources and the frontsubstrate including the phosphors ensures that the voltage resistancecharacteristic between the substrates is not deteriorated. Incidentally,in the flat panel display apparatus 2 such as an FED, a high voltage ofabout 5 kV, for example, is impressed between the substrates.

[0095] Furthermore, in the method of manufacturing the flat paneldisplay apparatus 2 according to the present invention, thenon-evaporation type getters 20 are fixed by press fitting into thespacers 10, whereby liberation of gas from an adhesive is obviated.Particularly, where a multiplicity of non-evaporation type getters aredispersedly disposed inside the gas-tight container of the flat paneldisplay apparatus by the conventional manufacturing method, there is theproblem of liberation of gas from the adhesive; on the other hand, inthe manufacturing method according to this embodiment, the bad effect ofan increase of liberation of gas is obviated. Besides, in themanufacturing method according to this embodiment, the need for maskingfor vapor deposition on the substrate is absent, and the bad effect ofthe masking is hence absent, as contrasted to the method of forming thenon-evaporation type getters in a predetermined pattern by a vapordeposition process.

[0096] Incidentally, the present invention is not limited to theabove-described embodiment, and various modifications are possiblewithin the scope of the invention.

[0097] For example, a specific shape of the non-evaporation type getteris not particularly limited; namely, for example, as shown in FIGS. 4Ato 4D, non-evaporation type getters 20 a to 20 d having various shapesmay be considered.

[0098] The non-evaporation type getter 20 a shown in FIG. 4A includes acylindrical non-evaporation type getter main body 22 a, and a pressfitting projected portion 26 a, which are integrally molded by powderinjection molding. The non-evaporation type getter 20 a is fixed bypress fitting into the fitting hole 11 in the spacer 10 in the samemanner as the non-evaporation type getter 20 shown in FIG. 2.

[0099] The non-evaporation type getter 20 b shown in FIG. 4B is in theshape of a cross, and is integrally molded by powder injection molding.The non-evaporation type getter 20 b is disposed at such a location asnot to overlap, in plan view, with the pattern of the phosphors 14 shownin FIG. 1.

[0100] The non-evaporation type getter 20 c shown in FIG. 4C functionsalso as at least a part of the spacer 10 c, and is integrally molded bypowder injection molding.

[0101] The non-evaporation type getter 20 d shown in FIG. 4D is in theshape of a rectangular frame, and is integrally molded by powderinjection molding. The non-evaporation type getter 20 d is disposed atsuch a location as not to overlap, in plan view, with the pattern of thephosphors 14 shown in FIG. 1.

EXAMPLES

[0102] Now, the present invention will be described more in detail belowbased on examples, which are not limitative.

Example 1

[0103] In powder injection molding, first, a metallic powder includingelemental Ti as a principal constituent and a binder were kneaded witheach other, to prepare an injection molding material. The average graindiameter of the metallic powder was 10 to 20 μm. Besides, as the binder,a paraffin-propylene based binder was used.

[0104] Next, the powder injection molding material was injected into amold having a cavity in the shape of the non-evaporation type getter 20c shown in FIG. 4C, to form a pre-molded body. Then, the bindercontained in the pre-molded body was removed. The process up to thisstage was carried out under the same conditions as in the ordinarypowder injection molding.

[0105] Subsequently, the pre-molded body was baked, to obtain a moldedbody composed of a sintered body. The baking temperature was 900° C. Theporosity of the molded body after sintering was 25%. An electronmicrophotograph of the molded body after sintering is shown in FIG. 6A.

[0106] Next, the molded body after sintering was subjected tomeasurement of gas absorbing capability (gettering characteristic) forcarbon monoxide (CO) gas. The measurement of gas absorbing capabilitywas carried out after the sintered body as a non-evaporation getter wassubjected to an activating treatment at 400° C. in a vacuum of 1×10⁻³ Pato 1 Pa for 2 hr and cooled. The result is represented by curve A1 inFIG. 5A.

[0107] In FIG. 5A, the axis of ordinates indicates the pressure at apredetermined location in a gas absorbing capability measuringinstrument, and the axis of abscissas indicates the lapse of time fromthe start of gas absorption. In this figure, the area defined betweenpressure straight line A0 corresponding to an absorbing capability of 0(zero) and curve A1 represents the gas absorbing capability. Namely, thelarger the area is, the higher the gas absorbing capability is. As shownin FIG. 5A, it was confirmed that a sufficiently high gas absorbingcapability can be obtained.

Comparative Example 1

[0108] A non-evaporation type getter composed singly of Zr and havingthe same shape and weight as those of the non-evaporation type gettersintered body in Example 1 was formed by an electron beam vapordeposition process. The non-evaporation type getter thus obtained wassubjected to measurement of gas absorbing capability in the same manneras in Example 1, except that the activating treatment was conducted at400% for 4 hr. The result is represented by curve A2 in FIG. 5A.

Comparative Example 2

[0109] A non-evaporation type getter composed singly of Ti and havingthe same shape and weight at those of the non-evaporation type gettersintered body in Example 1 was formed by an electron beam vapordeposition process. The non-evaporation type getter thus obtained wassubjected to measurement of gas absorbing capability in the same manneras in Example 1, except that the activating treatment was conducted at400° C. for 4 hr. The result is represented by curve A3 in FIG. 5A.

[0110] Evaluation

[0111] As shown in FIG. 5A, Comparative Examples 1 and 2 showed a higherinitial absorbing capability but showed a lower absorbing capabilityretention effect, as compared with Example 1; namely, the absorbingcapability rapidly decreased with the lapse of time in ComparativeExamples 1 and 2. The reason for the results is considered as follows.It is considered that, in the case of the vapor deposition type getter,it is difficult to form a getter with a stable pore condition, and theinside of the vapor-deposited film is rarely utilized as a getter. Onthe other hand, the getter in Example 1 showed a stable adsorbingcapability from the initial period to the final period, indicating ahigh reliability of gettering. It is considered that gas is adsorbedalso onto the inside of the getter composed of the sintered body, andthe entire part of the getter is utilized as a getter.

Example 2

[0112] A vapor-deposited film composed singly of Zr was formed by anelectron beam vapor deposition process on the surface of the sinteredbody getter obtained in Example 1, and the resulting getter wassubjected to the same gas absorbing capability test as in Example 1. Thethickness of the vapor-deposited film was 0.1 μm. The result isrepresented by curve A4 in FIG. 5B. In addition, an SEM sectionphotograph of the getter thus obtained is shown in FIG. 7.

[0113] As shown in FIG. 5B, the getter obtained in Example 2 showed afurther longer life of gas absorbing capability and, as a whole, anenhancement of absorbing capability up to about 10%, as compared withthe getter obtained in Example 1.

Example 3

[0114] A non-evaporation type getter composed of a sintered body wasformed in the same manner as in Example 1, except that the sinteringtemperature for the molded body was set to 950%. A section photograph ofthe getter thus obtained is shown in FIG. 6B. It was confirmed thatpores can be formed sufficiently by this method.

Reference Example 1

[0115] A non-evaporation type getter composed of a sintered body wasformed in the same manner as in Example 1, except that the sinteringtemperature for the molded body was set to 1100° C. A section photographof the getter thus obtained is shown in FIG. 6C. It was confirmed thatless pores can be formed by this method.

[0116] As has been described above, according to the present invention,it is possible to provide a non-evaporation type getter excellent inreliability of gas absorbing capability thereof, capable of maintainingthe inside of a gas-tight container in a display apparatus, particularlya flat panel display apparatus or the like, in a high vacuum condition,capable of being mounted easily, and less liable to contaminate theinside of the gas-tight container, a display apparatus including thegetters, and methods of manufacturing the same.

[0117] In addition, according to the present invention, it is possibleto provide a flat panel display apparatus in which a gradient ornonuniform distribution of the degree of vacuum can be suppressed overthe entire display region, the reliability of emission of electron beamsfrom electron emission sources such as field emission devices can beenhanced, and a longer life can be contrived, and a method ofmanufacturing the same.

1. A non-evaporation type getter comprising a molded body whichcomprises at least one element selected from the group consisting of Ti,Zr, Al, V, and Fe as a principal constituent thereof, said molded bodyformed by powder injection molding.
 2. A non-evaporation type getteraccording to claim 1, wherein said molded body is comprised of a porousbody having a porosity of 10 to 30%.
 3. A non-evaporation type getteraccording to claim 1, wherein a coating layer is provided on at least apart of said molded body.
 4. A non-evaporation type getter according toclaim 2, wherein a coating layer is provided on at least a part of saidmolded body.
 5. A non-evaporation type getter according to claim 3,wherein said coating layer comprises at least one element selected fromthe group consisting of Ti, Zr, Al, V, and Fe as a principal constituentthereof, and is formed on a surface of said molded body by thin filmforming means.
 6. A non-evaporation type getter according to claim 4,wherein said coating layer comprises at least one element selected fromthe group consisting of Ti, Zr, Al, V, and Fe as a principal constituentthereof, and is formed on a surface of said molded body by thin filmforming means.
 7. A non-evaporation type getter according to claim 3,wherein said molded body comprises Ti as a principal constituentthereof, and said coating layer comprises Zr as a principal constituentthereof.
 8. A non-evaporation type getter according to claim 4, whereinsaid molded body comprises Ti as a principal constituent thereof, andsaid coating layer comprises Zr as a principal constituent thereof.
 9. Adisplay apparatus wherein a non-evaporation type getter according to anyone of claims 1 to 8 is mounted in a gas-tight container in said displayapparatus.
 10. A cathode-ray tube wherein a non-evaporation type getteraccording to any one of claims 1 to 8 is mounted to a portion of acathode structure body.
 11. A flat panel display apparatus wherein anon-evaporation type getter according to any one of claims 1 to 8 ismounted in a gas-tight container formed between a front substrate and aback substrate.
 12. A flat panel display apparatus comprising: a backsubstrate comprising electron emission sources; a front substrate whichis so disposed as to define a gas-tight container space between itselfand said back substrate, and comprises phosphors for emitting light bybeing irradiated with electron beams emitted from said electron emissionsources; and one or more non-evaporation type getters which aredispersedly disposed in said gas-tight container space and each of whichcomprises a molded body comprising at least one element selected fromthe group consisting of Ti, Zr, Al, V, and Fe as a principal constituentthereof, said molded body formed by powder injection molding.
 13. A flatpanel display apparatus according to claim 12, wherein a spacer formaintaining a minute gap between said front substrate and said backsubstrate is provided in the inside of said gas-tight container space,and said non-evaporation type getters are each fixed by fitting into aportion of said spacer.
 14. A flat panel display apparatus according toclaim 12, wherein a spacer for maintaining a minute gap between saidfront substrate and said back substrate is provided in the inside ofsaid gas-tight container space, and said non-evaporation type getterseach function also as at least a part of said spacer.
 15. A flat paneldisplay apparatus according to any one of claims 12 to 14, wherein saidnon-evaporation type getters are disposed as such positions as not tohinder the emission of electron beams from said electron emissionsources toward said phosphors and not to be connected directly to saidfront substrate and said back substrate.
 16. A method of manufacturing anon-evaporation type getter, comprising the step of performing powderinjection molding by use of a metallic powder comprising at least oneelement selected from the group consisting of Ti, Zr, Al, V, and Fe as aprincipal constituent raw material to thereby obtain a molded bodyhaving a predetermined shape.
 17. A method of manufacturing anon-evaporation type getter according to claim 16, wherein the averagegrain diameter of said metallic powder is 10 to 20 μm.
 18. A method ofmanufacturing a non-evaporation type getter according to claim 16,wherein said molded body is sintered at a temperature of 60 to 90% basedon a sintering temperature at which the true density of said molded bodyafter sintering will be not less than 95%.
 19. A method of manufacturinga non-evaporation type getter according to claim 18, wherein the averagegrain diameter of said metallic powder is 10 to 20 μm.
 20. A method ofmanufacturing a non-evaporation type getter according to claim 18,wherein said sintering upon said powder injection molding is carried outin vacuum.
 21. A method of manufacturing a non-evaporation type getteraccording to claim 19, wherein said sintering upon said powder injectionmolding is carried out in vacuum.
 22. A method of manufacturing anon-evaporation type getter according to any one of claims 18 to 21,wherein a coating layer is formed by a thin film forming process on atleast a portion of the surface of said molded body after sintering. 23.A method of manufacturing a flat panel display apparatus, comprising thesteps of: performing powder injection molding by use of a metallicpowder comprising at least one element selected from the groupconsisting of Ti, Zr, Al, V, and Fe as a principal constituent rawmaterial to thereby obtain a non-evaporation type getter having apredetermined shape; preparing a back substrate comprising electronemission sources; preparing a front substrate comprising phosphors foremitting light by being irradiated with electron beams emitted from saidelectron emission sources; preparing a spacer for determining thespacing between said back substrate and said front substrate; pressfitting said non-evaporation type getter into said spacer; and joiningsaid back substrate and said front substrate to each other, with saidspacer therebetween into which said non-evaporation type getter has beenpress fitted, so as to define a gas-tight container space between saidsubstrates.